This work was accepted as a dissertation by the Faculty of Law at the University of Heidelberg in the winter semester of 1993/94. It takes into account international legal practice and doctrine up to August 1993. Later developments and publications that appeared after this date could only be incorporated in a few cases. At this point, I would like to thank, first and foremost, my doctoral supervisor, Rudolf Bernhardt, who has followed the development of this research with great patience. I also thank Prof. Dr. Dr. h.c. Lochen Abr. Frowein for serving as the second examiner of this work. Additionally, I would like to express my gratitude to Prof. Dr. Helmut Steinberger and Prof. Dr. Rüdiger Wolfrum for their willingness to include my study in the series of "Contributions" of the Institute. The idea for this research originated...